I would not have the slightest hesitation striking up a conversation with the folks.
Tell them what a nice rig they have and ask how it tows etc.
You might find they are newbies and can use some information. Likely
You might find they know better but it was just a short hop. It happens
You might find they have been towing that way for years. Not likely.
Over the years I have seen cars, vans, pickups and flat beds incredibly over loaded with furniture, college kids with stuff, farm crops, hay and such.
It may be scary but a doubt that it is illegal. Your half ton many be overloaded but if it is within the weight limit allowed by the license plate, it is legal.
The absolute last thing we need would be government intervention. Government regulations are rarely more than an excuse to expand the tax base.
